Thanks for the reply, I wish I could post a picture but don't see a way. The solenoid seems to be mounted on the side of the gearbox with 4 allen head screws. It gets power by switching the shift switch forward and reverse. It gets 12V via a test light in both directions. I now need to see if the problem is elect or hyd in the unit. I don't have a wiring schematic but need to now check for resistance on the coils for each direction. I would think with just leaky o rings on the plunger it would at least still try to go. That or the plunger is not moving to it's forward position at all for some other reason other than the coil.
Am I even close to understanding this system. I do little British cars, this is all new to me. It just worked before!
Thanks again, Terry